Experimental Evidence of Free Carrier Generation in 2D Hybrid Organic–Inorganic Perovskites

Despite the significant potential of 2D hybrid organic–inorganic perovskites (2DHOIPs) for high‐efficiency optoelectronics application‐comparable to their 3D counterparts, the fundamental carrier photogeneration remains unclear. In contrast to conventional ultrafast optical property characterization, we use ultrafast photocurrent spectroscopy to investigate the early‐time electrical properties of type‐I and type‐II 2DHOIPs by manipulating the quantum confinement and the dielectric quantum matching effect. We discovered that the high frequency dielectric quantum matching effect plays a major role in 2DHOIPs, demonstrated by their high carrier mobility ( µ ), near‐unity photogeneration quantum yield ( Φ ), below‐room temperature exciton binding energy ( E b ), and approaching 3D space factor ( DSF ). Our work shows that the optoelectronic performances of 2DHOIPs are comparable to their counterparts of 3DHOIPs.